Magnetizing current control strategies for nonlinear indirect field oriented control

The optimal choice of the flux level is of uttermost importance for operating an induction motor with field oriented control (FOC). In this paper expressions are derived to obtain maximum torque for both stator and rotor flux FOC with a nonlinear motor model. On the one hand it is shown that the expressions for nonlinear rotor flux FOC are only slightly more complex than for the linear case, while nonlinear stator flux FOC yields significantly more complex equations. On the other hand the equations for rotor flux FOC in the field weakening region are only slightly more complicated than those for the stator flux system. However, for rotor flux FOC, a fair approximation can be derived, which is easy to use